The present invention relates to a pneumatic tire, more particularly to a tread pattern of a motorcycle tire for running on rough terrain capable of improving the contact with the ground, braking performance and cornering performance.
In general, a motorcycle tire for running on rough terrain for example used in a motocross race is provided in the tread portion with a block pattern formed by a number of independent blocks so that the blocks dig into soft grounds such as sand and mud and increase the road grip to improve the cornering performance, braking performance and the like.
The cornering performance may be improved by increasing the effectual circumferential component of the edges of blocks existing in the ground contacting patch of the tire. The effectual circumferential component can be increased by circumferentially shifting the blocks from one another. But, such circumferential shifting can not increase the effectual axial component of the block edges. Instead, there is a possible of reducing the effectual axial component existing in the ground contacting patch.
The braking performance may be improved by adopting a block whose axial dimension is increased to increase the axial component of the block edges. In this case, if the circumferential dimension is also increased to increase the circumferential component of the block edges, then as the block size increase, the block becomes difficult to dig into soft grounds. Therefore, the circumferential dimension is not to be increased.
Thus, it is difficult to effectively improve the cornering performance and the braking performance at the same time.